Heil offers repair service on their headsets and other products:http://www.heilsound.com/amateur/repairs/index.php
They will also completely "refurbish to like new" condition
headsets for $64 plus $17 shipping. Don't know if this
covers missing/broken parts.By all means talk to them.
I had no audio on
one side of my Proset. They sent me specific instructions
on how to bypass or replace the "Phase Reversal Switch"
and I was able to do the repair myself.
73, Ken AD6KA